The chapel is on the plan of an elongated rectangle consisting of two square bays and an apse enclosed with three sides of a hexagon. On the vaulting three keystones have survived with a multi-leaf rosette and figural scenes (St Margaret of Antioch and St Michael the Archangel fighting the dragon). The chapel is the earliest part of the cathedral, as it was completed already in 1322. The richness of the architectural and sculptural decor is probably connected with its sepulchral function, as it was conceived as the final place of rest for Bishop Nanker. Originally the chapel contained an altar with a stone retable, but it was removed in the 14th century, and two parts of the retable have been installed in the facade on the sides of the main entrance.
We are all well aware that to enter this Cathedral can not be without emotion. More I say, you can not enter it without the internal tremor, without fear because it contains in it - as in almost no Cathedral of the world - the enormous size, which speaks to us in all our history, our entire past.cardinal Karol Wojtyla